T-cells that produce cytokines regulating the growth and function of B-cells, T-cells, etc. and control the immune system are referred to as helper T-cells (Th), which are classified into two types, type 1 helper T-cells (Th1 cells) and type 2 helper T-cells (Th2 cells) based on their cytokine production patterns. Th1 cells are known to produce IFN-γ, IL-2, etc. to activate cellular immunity and Th2 cells to produce IL-4, IL-5, etc. to activate humoral immunity. So-called immune balance generally refers to the balance between the Th1 cells and Th2 cells and is widely used as an index, etc. showing, for example, the allergic condition of a patient.
Allergies are a disease in which various allergic symptoms such as hey fever, rhinitis, and dermatitis are developed when the Th1/Th2 balance is disturbed and shifted abnormally towards the side of Th2 to cause the immune system to respond excessively against a foreign antigen which is harmless in nature. Allergies are classified into 4 types, type I to type IV, depending on the difference in the reaction mechanism. In Japan, the number of patients of type I allergies represented by perennial allergic rhinitis caused by house dust such as ticks and dust and seasonal allergic rhinitis caused by cedar pollens has been significantly increasing, and there is a concern that the number of patients will increase further in the future.
Type I allergies occur with a release of chemical mediators such as histamine by labrocytes upon their stimulation mainly by antigen-bound IgEs. Pollens and house dust came into a body are recognized as antigens to produce IgE antibodies specific to these antigens. The specific IgE antibodies then bind to Fc receptors on the surface of mast cells and basophils in the blood to become sensitized. After that, when the antigen comes into the body again, the antigen binds to the IgE antibody to form an antigen-antibody complex to cause a degranulation, and chemical mediators such as histamine and leukotriene in the granules are released and the actions of these mediators manifest as allergic symptoms.
Examples of drugs used against these allergic symptoms include antihistamines, leukotriene antagonists, thromboxane antagonists, Th2 cytokine inhibitors, mediator-release inhibitors, steroid drugs, etc. However, for example, antihistamines may cause drowsiness and thirst as side effects, while leukotriene antagonists are known to have side effects such as cytopenia and digestive trouble, and mediator-release inhibitors to have side effects such as digestive trouble and bladder inflammation-like symptoms. These drugs therefore are not always safe.
Due to the above background, lactic acid bacteria regulating immune balance and having an anti-allergic action have recently attracted attention as safer anti-allergic materials. For example, the followings have been reported: an IgE antibody production inhibitor comprising as an active ingredient bacterial cells of lactic acid bacteria selected from Lactobacillus acidophilus, Lactobacillus brevis, Lactobacillus buchneri, Lactobacillus casei, Lactobacillus delbrueckii, Lactobacillus fermentum, Lactobacillus helveticus, Lactobacillus kefir, Lactobacillus paracasei, Lactobacillus plantarum, Lactobacillus rhamnosus, Lactobacillus salivarius, Streptococcus thermophilus, Lactococcus lactis, Lactococcus plantarum, Lactococcus raffinolactis, Leuconostoc lactis, Leuconostoc mesenteroides, Enterococcus faecalis, and Enterococcus faecium (see Patent Document 1); an anti-allergic agent comprising as an active ingredient human-derived bifidobacteria selected from Bifidobacterium infantis, Bifidobacterium breve, Bifidobacterium longum, and Bifidobacterium bifidum (see Patent Document 2); a type 1 allergy suppressing agent having an histamine release suppressing effect, comprising as an active ingredient bacterial cells of lactic acid bacteria, Enterococcus faecalis (AD101 strain) and Lactobacillus reuteri (AD0002 strain), separated from the human intestinal bacterial group (see Patent Document 3); and a drink and food product having an anti-allergic function, containing as an active ingredient Lactobacillus paracasei (see Patent Document 4).
Further, the followings have been reported: a composition for enhancing immunity containing a mixed culture, or mixed bacterial cells or culture supernatant derived from the mixed culture of three to eight species of lactic acid bacteria and Saccharomyces cerevisiae, the lactic acid bacteria being selected from the group consisting of Lactobacillus delbrueckii, Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus fermentum, Lactobacillus casei, Lactobacillus rhamnosus, Lactococcus lactis and Streptococcus thermophilus, (see Patent Document 5); an anti-food allergy agent comprising Enterococcus faecium which is lactic acid bacteria stimulating gut immunity or type 1 helper T-cells (see Patent Document 6 and Patent Document 7); an anti-allergic agent comprising as an active ingredient Bacillus coagulans which is spore bearing lactic acid bacteria (see Patent Document 8); an anti-allergic agent comprising as an active ingredient viable bacteria, dead bacteria, or a processed product of bacterial cells of at least one lactic acid bacteria selected from lactic acid bacteria belonging to the plant-derived genus Lactobacillus, lactic acid bacteria belonging to the plant-derived genus Leuconostoc, and lactic acid bacteria belonging to the plant-derived genus Pediococcus (see Patent Document 9); fermented milk having an action of inducing the expression of interferon gamma, containing bacterial cells or bacterial-cell components of plural species of lactic acid bacteria selected from the group consisting of Lactobacillus casei, Lactobacillus plantarum, Lactococcus lactis subspecies lactis, and Lactococcus lactis subspecies cremoris (see Patent Document 10); and an anti-allergic agent comprising a Lactobacillus plantarum culture as an active ingredient (see Patent Document 11).
Still further, the followings have been reported: Pediococcus pentosaceus which has an immunostimulatory action and/or allergy suppressing action and is resistant to gastric juice (see Patent Document 12); lactic acid bacteria Streptococcus thermophilus characterized in having an immunostimulatory action (see Patent Document 13); lactic acid bacteria selected from Lactobacillus paracasei, Lactobacillus plantarum, Lactobacillus gasseri and Lactobacillus salivarius having an immunostimulatory action/anti-allergic action (see Patent Document 14); Lactobacillus acidophilus PM-A0002, Lactobacillus gasseri, Lactobacillus salivarius, Lactobacillus johnsonii, Lactobacillus acidophilus PM-A0013 that stimulate immune cells to secrete cytokines at an anti-allergic concentration (see Patent Document 15); an anti-allergic agent containing as an active ingredient lactic acid bacteria belonging to Leuconostoc mesenteroides having a high IgE antibody-production suppressing action and an anti-allergic action (see Patent Document 16); an agent for ameliorating pollen allergy symptoms, consisting of Lactobacillus bulgaricus, Lactobacillus rhamnosus, Lactobacillus acidophilus, or a cell surface layer or crude peptidoglycans thereof (see Patent Document 17); a composition for regulating immune balance, containing Lactobacillus paracasei bacterial cells and Bifidobacterium bifidum bacterial cells (see Patent Document 18); Lactobacillus brevis which has an immunostimulatory action and/or allergy suppressing action and is resistant to gastric juice (see Patent Document 19); an anti-allergic composition containing Lactobacillus delbrueckii, Enterococcus durans, Leuconostoc mesenteroides (see Patent Document 20); and an anti-allergic composition containing Lactobacillus crispatus (see Patent Document 21).